LESSER KNOWN NUTRITIONAL NEEDS:
What is less known to practicing physicians is that several other vitamins and minerals are associated with improved bone strength independent of vitamin D and calcium. As stated by Munger, et al., “The preoccupation to date with calcium has resulted in less emphasis on the role of other nutrients in bone quality and osteoporosis.” Examples of common insufficiencies in addition to Vitamin D and calcium are magnesium, silicon, vitamin K, and boron.
MAGNESIUM: Dietary sources of magnesium include almonds, cashews and peanuts. Other sources include raisin bran cereal, potato skins, brown rice, kidney beans, black-eyed peas and lentils. Eight ounces of milk has approximately 25 mg of magnesium. The recommended dietary allowance for optimum health is 320-420 mg [35]. Thus modest supplementation with 250 mg/day of magnesium is reasonable to support bone health.
SILICON: Silicon is another important contributor to bone health. Silicon is an essential nutrient and silicon deficiency is associated with poor skeletal development . The relationship between silicon and bone mineralization is poorly understood, but negative piezoelectric forces are generated and stimulate bone formation when collagen matrix is subjected to compression. Epidemiological studies report that dietary silicon intake of more than 40 mg/day correlates with increased bone mineral density, but the average dietary intake of silicon is 20-30 mg/day . Dietary sources of silicon include whole grains and cereals, carrots and green beans. Some types of mineral water also contain silicon in the form of orthosilicic acid . Beer is a rich source of silicon because of the processing of barley and hops . Men consume more silicon them women and this is primarily due to differences in beer consumption . Post-menopausal women rarely achieve 40 mg of silicon per day and average approximately 18 mg per day . Also, post-menopausal women may not absorb silicon as well as younger women.
VITAMIN K is another lesser known nutrient that is important for bone health. Vitamin K has several different forms, but vitamin K1 and K2 are the naturally occurring forms . The name for this vitamin comes from the German word “Koagulations Vitamin” because it is essential for coagulation of blood. Excessive vitamin K does not increase the risk of blood clots, but those taking warfariN for anticoagulation should avoid supplemental vitamin K because warfarin is a vitamin K antagonist . Insufficient vitamin K is associated with under-carboxylation of osteocalcin, osteopenia and increased fracture risk, while vitamin K supplementation reduces bone turnover and improves bone strength. Useful dietary sources of vitamin K include kale, collard greens, fresh spinach, Brussels sprouts, iceberg lettuce, and prunes. The optimum daily intake of vitamin K has been established as 90 µgm (micrograms) per day for women and 120 µgm per day for men. However, larger amounts may be needed for complete carboxylation of osteocalcin. intake [50]. This suggests that vitamin K improves bone properties that increase bone strength without increasing mineral content. Vitamin K has no toxicity except for those using warfarin, so supplementation with100 µgm/day would to achieve slightly more than the recommended daily allowance and may have beneficial effects on bone structure.
BORON: Boron is increasingly recognized as an element that has several health benefits including bone health . The precise mechanism of action of boron for bone health is unknown, but boron stabilizes and extends the half-life of vitamin D and estrogen . The Recommended Daily Allowance of boron has not been established, but no toxicity has not been identified and excess boron is rapidly excreted in the urine Thus, it is reasonable to supplement the diet with 1-3 mg of boron although this dietary need may also be met by increased consumption of foods such as prunes, raisins, dried apricots, or avocados.
These lesser known insufficiencies of magnesium, silicon, vitamin K, and boron are rarely explained to physicians although the more common insufficiencies of calcium, vitamin D and exercise are increasingly recognized as contributors to bone health. In addition to these essential nutrients, vitamin C, inositol and L-arginine have beneficial effects on bone health. These three nutrients have been correlated with increased bone mineral density and improved bone strength when provided in physiological amounts. The actions of these three factors are to improve various aspects of the bone formation and remodeling as well as calcium absorption and retention. Vitamin C is essential for the formation of collagen and for fracture healing. The evidence for supplemental vitamin C in the management of osteoporosis is weak, but increased bone mineral density has been noted in postmenopausal women taking vitamin C supplements . Inositol is a carbohydrate compound found in cantaloupe, grapefruit, oranges, and prunes [67]. It is also found in the form of phytate in whole grain.
Dietary arginine is available in dairy products, poultry, seafood, and meat in addition to nuts and oatmeal. There is some evidence that supplemental l-arginine influences vascular relaxation and should not be used as a supplement following myocardial infarction, especially in patients older than 60 years at time of infarct . Studies where arginine, inositol, and silicon were taken together demonstrated increased bone mineral density and increased bone strength. Mega-doses of these three supplements have been used without adverse effects as anti-oxidants (vitamin C), or to enhance sports performance (L-Arginine), or to improve psychiatric disorders (Inositol). However, mega-doses may not be required to influence bone health. Supplementing the diet with physiological amounts of these three nutrients may support bone health.